Sexual segregation in a wide-ranging marine predator is a consequence of habitat selection
Sexual segregation in a wide-ranging marine predator is a consequence of habitat selection
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DOI：
10.3354/meps11112
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发表时间：
2015-01-07
影响因子：
2.5
通讯作者：
Hamer, Keith C.
中科院分区：
文献类型：
--
作者：
Cleasby, Ian R.;Wakefield, Ewan D.;Hamer, Keith C.
性别隔离在许多物种中很常见，通常归因于种内竞争或栖息地选择。然而，很少有研究同时量化性别特异性觅食行为和栖息地利用。结合运动、潜水、稳定同位素和海洋学数据，研究了北方塘鹅桑塘（Morus bassanus）的性别隔离是否源于性别特异性栖息地的利用。在连续3个繁殖季节（2010-2012年）对季节性分层陆架海的繁殖鸟类觅食进行了跟踪。雌性的行程更长，觅食距离更远，δ C-13值比雄性低。雄性和雌性的觅食区域只有轻微重叠。在净初级产量（NPP）相对较高(3 mg C m（-2) d(-1)）和海表温度（SST）相对较低（15℃）的混合近岸水域，雄性比雌性觅食更多，这可能是由于在近岸的生产性混合水域觅食的结果。雌鱼在中等海温（12-15℃）的近海分层水域觅食最为频繁，但对NPP没有一致的响应。潜水行为的性别差异与栖息地使用的差异相对应：雄性会进行更长更深的u型潜水。这样的潜水是近岸觅食的特征，而更短、更浅的v型潜水更常发生在近海水域。体重较重的鸟类在v型潜水时潜得更深，但即使在控制体重的情况下，雌性的v型潜水也比雄性深。总之，这些结果表明塘鹅的性别隔离主要是由混合水域和分层水域之间的栖息地隔离驱动的，这反过来又导致了性别特异性的觅食行为和潜水深度。
Sexual segregation, common in many species, is usually attributed to intra-specific competition or habitat choice. However, few studies have simultaneously quantified sex-specific foraging behaviour and habitat use. We combined movement, diving, stable isotope and oceanographic data to test whether sexual segregation in northern gannets Morus bassanus results from sex-specific habitat use. Breeding birds foraging in a seasonally stratified shelf sea were tracked over 3 consecutive breeding seasons (2010-2012). Females made longer trips, foraged farther offshore and had lower delta C-13 values than males. Male and female foraging areas overlapped only slightly. Males foraged more in mixed coastal waters, where net primary production (NPP) was relatively high (>3 mg C m(-2) d(-1)) and sea-surface temperature (SST) was relatively low (15 degrees C) more than females, possibly as a consequence of foraging in productive mixed waters over offshore banks. Females foraged most frequently in stratified offshore waters, of intermediate SST (12-15 degrees C), but exhibited no consistent response to NPP. Sex-specific differences in diving behaviour corresponded with differences in habitat use: males made more long and deep U-shaped dives. Such dives were characteristic of inshore foraging, whereas shorter and shallower V-shaped dives occurred more often in offshore waters. Heavier birds attained greater depths during V-shaped dives, but even when controlling for body mass, females made deeper V-shaped dives than males. Together, these results indicate that sexual segregation in gannets is driven largely by habitat segregation between mixed and stratified waters, which in turn results in sex-specific foraging behaviour and dive depths.